标签: box

     Now Introduce  more information about electromagnetic shielding box: Many shielded equipment research and development businesses, in order to meet electromagnetic compatibility requirements for conductive coupling requires the use of filtering technology, filtering technology to assist in the use of the filter element; coupling the radiation need to be supplemented by the use of shielding technology.      Electromagnetic shielding box through the shell, boxes, panels made of a metal shield, will be limited to a method of electromagnetic waves within a certain area. Since the radiation is divided into near-zone field source, the magnetic field source and the far zone plane wave, and therefore shield shielding performance according to different radiation sources in material selection, structural shapes and apertures leakage control and other aspects are different.      In the current increasingly dense electromagnetic spectrum, a sharp increase in electromagnetic power density per unit volume, high and low level devices or equipment large number of mixed use and other factors lead to equipment and system electromagnetic environment deteriorating case, its importance becomes more prominent. In this chaotic electromagnetic interference environment, in order to better work of such high performance electromagnetic devices, electromagnetic shielding box on the essential.      Electromagnetic shielding box using conductive or magnetic material shells, plates, sets, and other various shapes shield the electromagnetic capacity constraints in a certain space range for suppressing interference metal body radiation, and conduction and radiation treatment to be measured in order to achieve wireless communication devices without interference device test environment.       Finally, Tojoin remind you that if you want the design to achieve the required shielding performance, you need to first determine the source of radiation, a clear frequency range, according to each band structure typical leak to determine the control element, and then select the appropriate shielding materials, design shield housing. More relevant knowledge and shielding me please the micro-channel scanning head or concerns of the blog.

One of the downsides of cables and connectors is that, by design, they typically conceal the copper wires they handle. While that's a good thing, it makes checking those wires for signal parameters—voltage, current, rise/fall, timing, and so on—difficult to impossible. Enter the breakout box: a small, inexpensive, usually passive piece of test equipment. Breakout boxes bring those signals out to where they can be observed with probes, while also passing the signals through. I owned two of those, now lost somewhere. One was for the once-common 25-wire RS-232 connector (Figure 1), the second was for the four-wire telephone line using an RJ-11 connector (Figure 2).   Figure 1. The RS-232 breakout box saved many an engineer while troubleshooting the communications link. Breakout boxes were fun to use. They made it fairly easy to observe a signal line with a voltmeter for basic checks, or an oscilloscope if needed. Some of the RS-232 boxes were more advanced, with LEDs on the signal lines to show their state and activity, and even small DIP switches so you could disable and then jumper key lines—all of which gave you the joyous feeling of being able to both observe and control.   Figure 2. Troubleshooting telecom lines is easy with an RJ-11 telco breakout adapter. Now, though, it looks as if the simple breakout box has seen its best days. Today's high-speed, fast-slewing, small-swing signals—sensitive as they are to capacitance, load, and even temperature—can't tolerate the relatively heavy hand, figuratively speaking, of just any casual probing you might do with a breakout box. If you want to observe a signal going to or through a connector, you probably should have designed-in the necessary buffered test points in your prototype design and fabrication. Alternately, you'll likely need to get a relatively expensive test box that picks off the signals you want to observe, while not interfering with their paths and transitions in a way that the signals would notice. There's not much we can do about this, as the reality of the physics of these signals is not something you can fool. It's the electronic TM version of Heisenberg's uncertainty principle. We live in a world of fast-moving signals and their precision connectors, and they don't like to be touched. Even a benign scope probe or careless finger can upset the careful balance of inductance, capacitance, and other factors that the signal and connector were designed to play with nicely. But I still think about those basic breakout boxes, and how much good they did in their days of glory. Certainly, there are some test tools that have been around "forever" and look as if they'll be staying around, whether in their original form (a basic, pencil-like logic probe, perhaps) or greatly improved implementation (DVMs, scopes). But there are some that are now relegated to the back of the closet, and that we probably won't be seeing or using much anymore.  

                                        TV box     Consumer Electronics are susceptible to damage caused by ESD, which can be generated from sources such as human contact or air discharge. Protection from these threats lies in the individual discrete protection for I/O ports at all equipment levels. Protection can also be provided at the system interconnecting ports. The protection schemes outlined are recommended for low insertion loss, high signal integrity and low noise/crosstalk with increasing bandwidth. CitrusCom's products provide protection from the effects of ESD/EFT/Surges as defined by IEC 61000-4-2, IEC 61000-4-4 and IEC 61000-4-5.

We toss the phrase "safety-critical system" around without reflecting much on its meaning. What does "safe" mean? Can you prove your system is safe? I doubt it, since that's rather analogous to proving the absence of bugs. There's really an epistemological problem with the notion of safety, since one can only create arguments for risks one understands, not the entire universe of possible risks. Does it even matter if a "system" is safe? A system – a black box, instrument, device or other stand-alone device might be "safe," but could be a disaster in practice. That system is undoubtedly just one component in a bigger product, and its interaction with the rest of the world may not be safe. The rest of the world includes people, and people are notoriously competent at injecting an idiot factor that defies most safety reasoning. A case in point: A couple of weeks ago I was on a long-haul flight and was pleased that the seat had a 110 VAC outlet to power the laptop. A 14 hour hop is about three times longer than my laptop battery lasts. But early in the flight I was engrossed in Jean Smith's new Eisenhower biography and sort of oblivious to my surroundings. Eventually looking up I noticed that my seatmate, a rather elderly Chinese woman, had her earbuds on and was trying to insert the 1/8" connector... into the power outlet!! ( see below )   The 110 VAC outlet is next to the screen A safety case for the power outlet would probably figure on low-amp fuses, proper grounding, and other parameters. But who would factor in "elderly" and "earbud"? Even more confounding, the outlet was of the North American three-prong configuration, which was possibly foreign to this Chinese national. ( I once knew a Thai woman who had grown up in a bamboo shack with no electricity – it's probably dangerous to assume any familiarity with technology when catering to the general public ). Was she an idiot? Of course not. On reflection, it's sort of logical to expect the audio socket to be near the screen instead of hidden on the armrest.